QoS provisioning for multiple non‐real‐time services in cellular wireless networks

Future mobile services are expected to include various non‐voice oriented services. One important category of non‐voice oriented mobile services is non‐real‐time services. When a mobile user establishes a connection to access non‐real‐time service, the mobile user usually cares about whether the total time to complete its data transfer is within its time tolerance. In addition, different mobile users may have different bandwidth requirements and different tolerances in the total completion time. It is essential for wireless systems to provide various mobile users with different total completion times. In this paper, two quality‐of‐service (QoS) metrics, called stretch ratio and eligibility percentage, are employed at a connection level to present the degree of the length of the total completion time. We devise a measurement based call admission control scheme that provides multiple QoSs for various mobile users which have different requirements of stretch ratios, eligibility percentages, and bandwidths. Extensive simulation results show that the measurement based call admission control scheme not only provides various satisfactory QoSs for mobile users but also produces high throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

A generalized method for the inherent energy performance modeling of machine tools

Machine tools (MTs), as the key equipment of manufacturing systems, have enormous quantities and consume a great amount of energy. However, the diversity of both machines and their energy consumption properties make it difficult to transfer the energy-saving knowledge and services among different MT. To facilitate the initialization configuration of energy-saving services, the inherent energy performance (IEP) is investigated to describe the differences in energy consumption among MTs, and a generalized method for modeling the IEP of MT and its electrical subsystems is proposed. Three key enablers, including generalized experimental design rules, automatic coding, and data processing algorithms, are presented and integrated into a supporting system to reduce the modeling efforts and knowledge requirements. Case studies of an offline manufacturing scenario and an Internet of Things (IoT)-enabled manufacturing scenario were carried out to verify the effectiveness and convenience of the proposed method. The results show that the proposed method can provide essential modeling support for large-scale energy-saving service configurations and energy-efficient MT development.     

Refurbishment or quality recovery: joint quality and pricing decisions for new product development

Refurbishment and quality recovery, as two important strategies of reverse logistics, have been widely used for consumer durables, especially consumer electronics. This trend is driven by manufacturers’ profit-seeking behaviours and the increasing environmental concerns of society. This study investigates and compares the optimal emergence of these two strategies when product quality is endogenous. Model analyses provide several notable insights. First, we find that the refurbishment strategy dominates the quality recovery strategy when the fraction of the recoverable quality-inducing components in the defective product is low enough. Moreover, when the refurbishment strategy emerges as the optimum, the quality and price of the new product as well as the total realised sales of both new and refurbished products are consistently higher than those with the quality recovery strategy. In addition, when either the refurbishment or quality recovery strategy emerges as the optimum, the overall consumer surplus is also enhanced. Finally, in the model generalisation, we show that a synthetic strategy with which some of the returned defective products are refurbished and others are remanufactured through quality recovery can certainly increase the manufacturers’ profit compared to either one of them when the fraction of the recoverable quality-inducing components in the defective product is moderate.     

基于顾客退货的风险规避型双渠道供应链最优策略

在随机市场需求条件下,考虑风险规避型双渠道供应链中存在顾客退货时的最优决策问题,决策变量为两个渠道的商品售价和制造商批发价。以集中决策时的最优决策作为比较标杆,重点利用均值—方差方法分析了分散决策时风险规避型制造商和零售商的最优决策。结合灵敏度分析和数值试验,讨论了分散决策下的风险规避度,以及市场需求波动和顾客退货率对最优决策的影响。结果表明,高退货率不利于零售商、制造商及整个供应链的收益;风险规避度对收益的影响不是一成不变的,与需求波动大小有关;分散决策虽然引起了双边际效应,但制造商风险规避度的增加将降低双边际效应的负面影响。     

Modeling trade-offs among ecosystem services in agricultural production systems

Although agricultural ecosystems can provide humans with a wide set of benefits agricultural production system management is mainly driven by food production. As a consequence, a need to ensure food security globally has been accompanied by a significant decline in the state of ecosystems. In order to reduce negative trade-offs and identify potential synergies it is necessary to improve our understanding of the relationships between various ecosystem services (ES) as well as the impacts of farm management on ES provision. We present a spatially explicit application that captures and quantifies ES trade-offs in the crop systems of Llanada Alavesa in the Basque Country. Our analysis presents a quantitative assessment of selected ES including crop yield, water supply and quality, climate regulation and air quality. The study is conducted using semantic meta-modeling, a technique that enables flexible integration of models to overcome the service-by-service modeling approach applied traditionally in ES assessment.     

Resource allocation for multi-class services in multipath networks

In multipath networks, multiple paths are available for each pair of source and destination and can be used to carry data packets parallelly. It has been recognized that using multipath could promote the transmission reliability and fault tolerance, and improve the performance of increasingly bandwidth-hungry multi-media applications. In this paper we propose the resource allocation model for multi-class services in multipath networks with the objective of utility maximization, which is an intrinsically difficult problem of nonconvex optimization. We firstly analyze the model for only elastic services and obtain the optimal rate allocation for them. Then we also discuss the model for inelastic services with nonconcave (sigmoidal or discontinuous) utilities which share common links with elastic ones, and obtain some sufficient conditions under which the global optimum for both elastic and inelastic services can be obtained. For the nonconvex optimization problem, we present a heuristic algorithm using Particle Swarm Optimization (PSO), which can lead to improved solutions over existing approaches. Finally, some numerical examples are given to verify the results obtained.     

基于双边市场理论的云制造平台定价策略

基于双边市场理论,分析了垄断的云制造平台在收取会员费和交易费模式下的最优定价策略,并利用数值仿真分析了两种收费模式下平台最优利润的差异。结果表明:两种模式下的单边最优定价均与缴费方的自网络外部性系数和免费方的交叉网络外部性系数负相关,与免费方用户数量正相关,双边最优定价受各参数影响方向取决于供需方各参数的相对大小;单边定价对象为用户数量相对较多一方,平台两边用户数量相对平衡时,单边最优定价等于双边最优定价,双边定价时的平台最优利润高于单边定价;最优定价策略由平台内交易次数决定,交易次数较多时双边收取交易费模式更优,交易次数较少时双边收取会员费更优,交易次数临界值取决于平台内网络效应和用户数量。     

Estimation of fog utility pricing: a bio-inspired optimisation techniques' perspective

ABSTRACT

Due to the limited data storage capacity available to Internet service providers and large-scale enterprises, the concept of resource sharing arises. The services can be given on lease to enterprises through Service Level Agreements. Being the extension of the cloud computing, fog computing architecture brings the resources near end users. In order to get the services on lease, the enterprises are supposed to pay for the resources or services which are being used by them. In this paper, four nature inspired algorithms are analysed in order to determine the efficient management of services or resources so that the cost of resources can be reduced and the billing can be attained through calculation of the utilised resources. Pigeon inspired optimization, enhanced differential evolution, binary bat algorithm and simple human learning optimization are used to evaluate the energy consumed by the edge nodes or cloudlets that in turn can be used for estimating the bill through the Time of Use pricing variable. We evaluate the aforementioned techniques to analyse their performance regarding the bill calculation on the basis of fog servers usage. Simulation results demonstrate that BAT algorithm gives significantly better results than other three algorithms in terms of resource utilisation and bill reduction.     

Modelling Australian land use competition and ecosystem services with food price feedbacks at high spatial resolution

In a globalised world, land use change outlooks are influenced by both locally heterogeneous land attributes and world markets. We demonstrate the importance of high resolution land heterogeneity representation in understanding local impacts of future global scenarios with carbon markets and land competition influencing food prices. A methodologically unique Australian continental model is presented with bottom-up parcel scale granularity in land use change, food, carbon, water, and biodiversity ecosystem service supply determination, and partial equilibrium food price impacts of land competition. We show that food price feedbacks produce modest aggregate national land use and ecosystem service supply changes. However, high resolution results show amplified land use change and ecosystem service impact in some places and muted impacts in other areas relative to national averages. We conclude that fine granularity modelling of geographic diversity produces local land use change and ecosystem service impact insights not discernible with other approaches.     

物联网环境下基于情境的语义Web服务选择

当前Web服务海量增加，物联网应用技术快速发展、不断普及，而现有的Web服务选择算法低效、用户匹配度低。针对该问题提出一种物联网环境下基于情境的语义Web服务选择方法。该方法应用QoS参数的无量纲化与语义Web服务动态选择方式，将物联网环境下服务与语义Web服务相结合，并根据用户需求针对QoS选择最优的服务集。实验表明，该方法能有效地提高用户服务动态选择的成功率。